All-in-one dual-function porous materials derived from polyacrylonitrile for high-performance supercapacitor

Abstract

Polyacrylonitrile (PAN)-based multifunctional energy storage materials have garnered significant interest in the research community. However, developing multifunctional PAN porous materials for integrated supercapacitors has encountered challenges such as low energy density, insufficient separator wettability, and limited ion conductivity. Herein, two types of versatile PAN-based dual-function porous membranes with varying pore sizes were fabricated using straightforward techniques involving solvent exchange and a directed freezing freeze-drying process. Subsequently, a high-performance-separator (POS) was developed by modifying pristine porous PAN with tetraethoxysilane (TEOS). Energy storage materials (CPAN-MnO₂) were fabricated by depositing MnO₂ onto the porous carbonised PAN (CPAN) surface through electrodeposition. The resulting structure, with CPAN-MnO₂ as the energy storage unit and POS as the separator, achieved an impressive ion conductivity of 32.2 mS cm⁻¹, super hydrophilicity, and high electrolyte uptake (456 %) and retention (302 %). A symmetric supercapacitor (SC) using CPAN-MnO₂ and POS demonstrated a maximum energy density of 163 μWh cm⁻² and exceptional cyclic stability, with 93.6 % capacitance retention after 10,000 cycles. This superior energy storage performance can be attributed to the TEOS-modified PAN porous channels, which enhance wettability with the electrolyte, improving electrolyte uptake and retention within the porous framework for ion exchange, thereby enhancing the electrochemical performance.